Recently, as energy consumption is increased, a solar cell has been developed to convert solar energy into electrical energy.
In particular, a CIGS-based solar cell, which is a PN hetero junction apparatus having a substrate structure including a glass substrate, a metallic back electrode layer, a P type CIGS-based light absorbing layer, a high resistance buffer layer, and an N type window layer, has been extensively used.
In addition, the solar cell can represent improved efficiency due to the electrical characteristics such as low resistance and high transmittance.